Contact lenses are often tinted for protecting the eyes against bright light or for cosmetic purposes, either to enhance the color of the eyes or to conceal disfigurements. Tinting is usually done with transparent dyes which can change or enhance the apparent color of a light colored iris. Recently the patents of C. W. Neefe, e.g., U.S. Pat. Nos. 4,460,523 and 4,472,327 have proposed a new kind of coloring technique for contact lenses which can actually change the apparent color of even a dark colored iris instead of merely enhancing the natural color. For example, a brown iris can be made to appear blue with such lenses. The technique of the Neefe patents is to incorporate in the lens material a mixture of transparent dye and reflective opaque particles such as titanium dioxide. A lens of this kind can mask the color of a dark iris and can change the apparent color to a lighter color.
A drawback of known tinted lenses, including these which contain only a dye and those which contain both a dye and opaque reflective particles, is that the lens has a uniform color and does not have the variegated pattern which characterizes the natural iris. To some extent the natural iris pattern may show through a lens which contains only a transparent dye but even with such lenses the iris pattern seems unnatural. Tinted lenses in general, and especially lenses containing opaque reflective particles, give an unnatural appearance to the eye which is sometimes called the lizard or bug-eye look.
To overcome the unnatural appearance of a uniformly colored iris, efforts have been made to form a variegated iris pattern on tinted lenses, as shown by the following references.
The patent to Le Grand et al, U.S. Pat. No. 3,712,718 discloses a plastic corneal contact lens having a transparent central zone and an irregular pattern of colored striations in the surrounding peripheral zone. The striations are cut or otherwise formed to a certain depth in the concave face of the lens. Then they are filled with an acrylic monomer and a translucent colorant. Next the material filling the striation cuts is cured to bond it to the transparent lens material.
The patent to Spivack, U.S. Pat. No. 3,536,386, also discloses a plastic contact lens with a simulated iris pattern. The lens is formed of two concentric halves with a imprinted iris pattern sandwiched between them.
While these earlier patents disclose methods which may or may not produce a natural looking iris pattern on a lens, the manipulative steps are complex and would add substantially to the cost of the lenses. Furthermore, it does not appear that their techniques would be at all useful with soft hydrogel contact lenses.